Book crunch (V-up)

Coreintermediaterepsno equipment

Also called V-up or jackknife. From lying flat with straight arms overhead and straight legs, the upper body and the legs lift at the same time and fold together like a book closing: at the top the body balances on the buttocks in a V and the hands touch the feet. Arms and legs stay straight throughout; the abdominals do the work.

How to do it

1. Lie on your back, legs straight and together, arms straight on the floor overhead.
2. Brace the abdominals and lift arms, head, shoulders and straight legs together in one movement.
3. At the top balance on the buttocks in a V and touch the feet (or the shins) with the hands, chest open, legs straight.
4. Lower arms and legs back down with control, without letting the lower back arch, and repeat. Bend the knees slightly to make it easier.

Muscles worked

Main: abs
Supporting: quads, obliques, shoulders